The invention relates to a method for the automatic adjustment of a high-resolution electronic balance, in which the changes in parameters affecting the balance are detected and processed by an evaluation circuit of the balance and/or a microprocessor.
In high resolution balances, changes in parameters (or disturbance variables) such as temperature, air pressure, aging of the components, etc., affect the balance so that the indicated weight is not correct. A periodic adjustment of the balance therefore is absolutely necessary.
Error compensation methods for electronic high-resolution balances are known. From DE-A1-31 06 534 it is known to detect the current air pressure and continuously to take the detected value into consideration in the electronic evaluation of the weight.
In CH-PS 624 773, correction values for several components which can affect the measurement result are detected and recorded. Moreover, temperature coefficients and changes in values caused by age are detected and taken into consideration by a computer in the calculation of the final measurement result.
These known error compensation methods use changes in values of the factors affecting the measurement result for continuous correction of the calculated measurement result. But such continuous correction of a high-resolution balance makes the adjustment procedure very expensive because the sensors necessary for detection of the external disturbance variables (temperature, etc.) must work very precisely for continuous detection and must produce reproducible values.
Another known method described in EU-A1-0 044 707 comprises an automatic recalibration which is triggered if a specific time has passed or a given number of weighings have been made or after each taring. Such a rigid recalibration rule results in recalibration being performed when objectively it would not be necessary, and thus constitutes an often unnecessary disturbance during a series of weighings.
Only a small part of the adjustment problems can be solved with the known processes.